9 LTOS7 Management and Monitoring
Particularity LANTIME/MRS:
All external NTP servers will be added to the NTP configuration file /etc/ntp.conf as "noselect". This has the
effect that all servers are requested by the NTPD for statistic purposes, but the servers are never selected by
the NTPD as synchronization peer. The LANTIME MRS logic then selects the best server among all servers.
The selection algorithm for the best external NTP server is separated in the following steps:
-
select which server is accepted
-
create groups of different offsets
-
select the biggest group
-
check for outliers and remove them from that group
-
use the median as best-server
-
check if last_best_external_NTP_server can be used -
to reduce clock hopping
The best server can be checked in the Web Interface under "Statistics
→
NTP Status" and under "Clock
→
Status & Configuration
→
MRS Status". The determined offset is then used to discipline the internal oscillator
in case no other reference source with a higher priority is available.
Due to this particularity, the configuration possibilities for external NTP server are different. The parame-
ters Minpoll, Maxpoll and Iburst cannot be configured on a LANTIME/MRS.
For a LANTIME/MRS you can adjust the default polling interval of 32 seconds via the manual configura-
tion of the server. To proceed follow this menu navigation:
Web Interface - "System Page
→
Services and Functions
→
Manual Configuration
→
Standard Configura-
tion
→
Miscellaneous Configuration"
You can use the parameter "MRS NTP POLL INTERVAL" to adjust the polling interval of the external server.
As per default this value is set to 0, which means that external are queried every 32 seconds. Values can be
set between 1 and 10 and are used as a power of 2. For example if this value is set to 6, this is equal to 2
6
=
64 seconds for a polling interval.
Use the parameter „MRS NUM NTP PACKETS PER POLL“ to set the number of NTP queries sent per
polling interval. Per default this value is set to 0, which means that 4 packets are sent in a given polling
interval. Set a value between 1 and 8, which corresponds to the actual number of packets.
LANTIME CPU Expansion Shelf
Date: 2nd July 2020
77
Summary of Contents for LCES
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